Effects of strychnine and picrotoxin on the activity of laryngeal and phrenic motoneurons during stimulation of vagus nerve.

Effects of strychnine and picrotoxin on the activity of laryngeal and phrenic motoneurons during stimulation of vagus nerve. Acta Physiol. Pol., 1977, 28 (1): 1-11. In paralyzed cats the activity of "single fibres" in the recurrent laryngeal nerve and phrenic nerve was recorded. The afferent part of the vagus nerve was stimulated electrically at a frequency of 200 Hz, the duration of one impulse was 1 msec and voltage values used were 0.1, 0.2 and 0.3 V. Stimulation was carried out in paralyzed animals and then after intravenous administration of strychnine 0.3 mg/kg and picrotoxin 1.0 mg/kg. Administration of the drugs was sufficient to induce in both nerves appearance of additional impulses of varying amplitude. Stimulation after administration of strychnine and picrotoxin caused partial inhibition of the activity of both nerves (less significant than before administration of drugs). The authors believe that the mechanisms of presynaptic and postsynaptic inhibition participate in the activity of nervous pathways conveying the inhibitory effect of the vagus nerve to the laryngeal and phrenic motor neurons.